In providing telecommunications via optical fiber cable between locations sufficiently remote to justify the cable's underground installation, the cable is oridinarily passed through underground ducts to which access is obtained by manholes. For purposes of protecting the cable from damage, such ducts usually contain one or more bodies of synthetic resinous piping (commonly known in the art as "inner duct") so placed in the ducts that, at the opening of a duct into a manhole, a length of the inner duct projects beyond that opening to terminate in a free end often formed by cutting the inner duct and having an annular front face with inner and outer peripheral edges. Such inner duct length is relatively stiff, and the mentioned edges of its front face are quite hard and sharp and may be somewhat jagged. Also, in the course of feeding an optical fiber cable or a preceding flexible elongated product into such length without the benefit of a guide, the front end of the cable or other product or hardware associated with either of them may snag against the front of the inner duct to be damaged or cause damage.